Steam-turbine.



C. E. SEARCH.

STEAM TURBINE.

APPLICATION man AuG.15.191A. RENEwED Nov. 15.1915.

Patented June 13, 1916.

2 SHEETS-SHEET I.

C. E. SEARCH.

y STEAM TURBINE.

APPLICATION FILED AUG. 15. 1914. RENEWED Nov. 15.1915.

Patented June 13, 1916.

2 SHEETS-SHEET 2.

5 5 'Iliff/1111111153 A @27AM/wacom Maia@ CHARLES EDWIN SEARCH, OFMILWAUKEE, WISCONSIN, ASSIGNOR TO ALLIS-CHALMERS MANUFACTURING COMPANY,OF MILWAUKEE, WISCONSIN, A CORPORATION OF WISCONSIN.

Original application led February 9, 1914, Serial No. 818,156. Dividedand this application filed August i Specieation of Letters ratent.

Patented June 13, 1916.

15, 1914, Serial No. 856,984. Renewed November 15, 1915. Serial No.62,073.

To all Iwhom, t may concern Be it known that I, CHARLES EDWIN SmnCH, acitizen of the United States, residing at Milwaukee, in the county ofMilwaukee and State of Wisconsin, have invented a certain new and usefulImprovement in Steam-Turbines, of which the following is aspecification.

This invention relates to steam turbines and more particularly to meansfor securing the shroud to the blade ends and for properly positioningthe blades at one end.

An object of the invention is to provide a blade structure for steamturbines and similar devices which is simple and light in construction,eflicient j in operation, and which possesses the requisite amount ofrigidity and strength, especially to withstand vibration.

One of the more specific objects of the invention is to provide a verylight longitudinally corrugated shroud having formed thereon means forproperly spacing and angling single-surfaced blade ends, the shroudbeing secured to the blade ends by fusion of metal.

Another object is to provide a simple method of forming the means forpositioning the blade ends by forming positioning surfaces on thecorrugation in such a way as to coact with the working faces of theblades longitudinally to a considerable eX- tent.

This application is a division of application Serial No. 818,156, filedFebruary 9, 1914.

The expression single-surfaced end as used herein is intended to applyto a blade end which is free of any projection or recess abruptlyinterrupting the continuity of the end surface of the blade. The eX-pression therefore includes blade ends having surfaces which are eitherplane or curved, these surfaces being either perpendicular or obliquerelative to the edges of the blade.

It has heretofore been proposed to fasten a shroud to the ends ofturbine blades by forming tenons at the ends of the blades which werepassed through holes in the shroud and were riveted over at theirprotruding ends. It has also been proposed to fasten alight shroud tothe ends of blades by fusion of metal, for instance by brazing,

and also increasing the' cost of construction.

With the device of the present invention these objections lareeliminated. In addition, the corrugation of the shroud of the presentinvention combined with its fastening to the blade ends by fusion ofmetal makes the shroud in the completed structure very much stiffer andstronger.

A clear conception of several embodiments of the invention may be had byreferrmg to the drawing accompanying and forming a part of thisspecification in which l1ke re ference characters designate the same orsimllar parts in the various views. v

Figure l is a plan view of a fragment of one form of shroud attached toa plurality of blades. Fig. Q is a transverse vertical section throughfragments of the shroud and blades disclosed in Fig. l, the sectionbeing taken along the line II-II of Fig. 1 looking 1n the direction ofthe arrow. Fig. 3 is a transverse vertical section through the shrouddisclosed in Fig. 1, showing the same attached to a fragment of a blade,the section 4being taken at a portion of the shroud between successiveblades. Fig. 4 is a transverse vertical section through the shrouddisclosed in Fig. l, showing the same attached to a fragment of a blade,the section being taken at one of the working faces of the blade. Fig. 5is a plan view of a fragment of another form of shroud attached to aplurality of blades. Fig. 6 is a transverse vertical section throughfragments of the shroud and blades disclosed in Fig. 5, the sectionbeing taken along the line VI-VI of Fig. 5. Fig. 7 is a transversevertical section through the shroud disclosed in Fig. 5, showing thesame attached to a fragment of a blade, the section being takenat aportion of the shroud between successive blades. Fig.

. 8 is a transverse verticalsection through the shroud disclosed in Fig.5, showing the same attached to a fragment of a blade, the section beingtaken at. one of the working faces of the blade. Fig. 9 isa plan view ofa fragment of still another form of shroud attached to a'plurality ofblades. Fig. 10 is a transverse vertical section through fragments ofthe shroud and blades disclosed fin Fi 9, the

section being taken along the line -X of Fig. 9. Fig. 11 is a transversevertical section through the shroud disclosed in Fig. 9, showing thesame attached to a fragment of a blade, the section being taken at aportion of the shroud between successive blades. Fig. 12 is a transversevertical section through the shroud disclosed in 'Figa 9, showing thesame attached to a fragment of a blade, thel section being4 taken at oneof the working faces of the blade. Fi ..13

is a transverse vertical section through rag- -ments of still anotherform of shroud and blades, the section being taken along the line'XIII-XIII of Fig. 14. Fig. 14 is al transverse sectional view through aplurality of blades having attached thereto a fragment of the shroudvasdisclosed in Fig. 13, the section being taken near the blade ends. Fig.15 is a transverse vertical section through the shroud disclosed in Fig.13, showing the same attached to a fragment of a blade, the

section being taken at a portion of the shroud taken near the bladeends. Fig. 19 is a transverse vertical section through the shrouddisclosed in Fig. 17, showing the same attached to a fragment of ablade, the section being taken at a portion of the shroud betweensuccessive blades. Fig. 20 is a transverse vertical section through theshroud disclosed in Fig. 17, showing the same attached to a fragment ofa blade, the section being taken at one of the working faces of theblade;

While the figures of the drawing in each case disclose rotor or movableblading of a parallel flow turbine of the Parsons type,

it is to be understood that the invention is equally applicable tostator or stationary blading, as well as to other types of turbines. Theshroud in each case is made very light and is provided with parallelside walls for vthe purpose of facilitating machining of theassembled-structure, in order to secure a close tit between the shroudand thev stationary turbine casing. This invention is not, however,limited to channel `\.jection 7 may be formed by distortion of shroudstock normally having either a cylindrical or plane base portion, but ispreferably formed during the manufacture of the shroud stock, either byrolling or drawing, and forms a continuous longitudinal arch on theshroud which greatly enhances the stiffness of the shroud stock. Inorder to provide means for positioning, that is, properly spacingy andangling the blade ends, the shroud 2 is provided with a series ofpunched holes 3 passing transversely therethrough at the corrugation orprojection 7 to form recesses inthe projectlon. The surfaces of two'opposite walls of the holes 3 conform to the contour of the workingfaces of the blades, and coact therewith longitudinally to aconsiderable extent. The holes 3 are formed by means of a die which isof a projected width equal to the maximum width of the projection 7.After the recesses in the projection 7 have been formed by the formationof the holes 3, the shroud 2 is applied to the single-surfaced bladeends and is united thereto by fusion ofmetal,

either by soldering, brazing, welding or in any other way. In thedrawings the union has been made by brazing, the added fusible materialbeing represented as a fillet 5 adjacent the ends of the blades.

Referring specifically to Figs. 5, 6, 7 and 8, the channel shaped shroud12 is formed of` stock having a continuous longitudinal corrugation orprojection 17 .near the mid port-ion thereof, this corrugation beingformed as indicated hereinabove. The means for positioning, that is,properly and coacting therewithlongitudinally to a considerable extent.After the recesses have been formed. 1n the projections 17, the

spacing and angling the blade ends, is proshroud 12 is applied to thesingle-surfaced of metal as indicated hereinabove. In the drawing thisunion has been indicated as having 'been accomplished by brazing, theadded fusible material being represented by fillets 15 adjacent the endsof the blades 1. The shearing of the metal of the projection 17 is not,however, to be considered as perforating, as this term is intended toapply only to the form of shroud disclosed in Figs. 1 to 4 inclusive.

Referring specifically to Figs. 9, 10, 11'

and 12, the channel shaped shroud 22 is` formed of stock which primarilyhas a continuous longitudinal corrugation or projection 27 near the midportion thereof. This corrugation is again preferably formed asindicated hereinabove. The means for positioning the blade endsconsists'of a series of transverse recesses in the projection 27, theserecesses being formed by forcing back the portions 23 of the projection27 so as to bring the same into alineinent with the normal base of theshroud 22. The recesses are thus formed with opposite walls havingsurfaces conforming to the contour of the Work- 'ing faces of the blades1 and coacting therewith longitudinally to a considerable extent, butnot to the same degree as in the forms hereinabove described. After therecesses have been formed, the shroud 22 is applied to thesingle-surfaced blade ends and is united thereto by fusion of metal, theadded fusible material being represented as fillets 25 adjacent the endsof the blades 1.

Referring specifically to Figs. 13, 14, 15 and 16, the channel shapedshroud 32 is formed of stock having a pair 'of substantially parallelcontinuous longitudinal projections 37 extending along the blade sidethereof. These projections 37 are preferably formed during themanufacture of the shroud stock either by rolling or drawing the shroudstrip with the continuous projections thereon. The means for properlypositioning the blade ends are produced by forming a series of recessesin the projections 37. The recesses are formed with opposite wallshaving surfaces conforming to the contour of the working faces of `theblades 1 and coacting therewith longitudinally to a considerable extent.The recesses in the projections 37 are formed by forcing back the metalof the projections wherever it is desired to have a recess, permittingthe metal so displaced from the projections to build up inthe form oflow, spread-out mounds or projections 33 on the outer side of the shroudbase. After the recesses have been properly formed in the projections37, the shroud 32 is applied to the single-surfaced ends of the bladesand is united thereto by fusion vof metal as indicated hereinabove. Thisconstruction has the advantage that the backingl die used in forming there cesses does not necessarily have to be reached 1n order to permitfeeding forward of the shroud stock which is secured to anintermittently fed support. In this case the shroud st ock will'springsufficiently to -permit the dislocation of the mound from the stationarybacking die. It is preferable, however, to recede the backing die forthis purpose.

Referring specifically to Figs. 17, 18, 19 and 20, the channel shapedshroud 42 is formed of stockhaving a surface on the blade side thereof-comprised of rectilinear transverse elements. The means for prop- "erlypositioning the blade ends are produced by first locally distorting theshroud base to form projections 47 on the blade side thereof, afterwhich the portions of the projections 47 in line with the blades arerestored to form recesses at the desired portions thereof, by forcingback the portions 43 of the proi jections 47 to bring these portions 43into re-alinernent With the shroud base. The recesses are formed withopposite wallshaving surfaces conforming to the contour of the workingfaces of the blades 1 and coacting therewith longitudinally to aconsider- I ab e y13 to 16 inclusive, the mounds 33 are so low andspread-out as to produce substantially no retardation of the turbinerotor. The form of shroud 42 disclosed in Figs. 17 to 20 inclusive,would produce substantially no retardation to the rotation of the rotoras there are no local projections extending outwardly from the normalbase of the shroud. The forms of shroud 32, 42, shown inFigs. 13 to 20,inclusive, are especially applicable to the larger sizes of bladingbecause of the increased distance between the limits of transversecontact between the positioning surfaces and one of the working faces ofthe blade.

It will be noted that with all of the constructions herein disclosed, ablade 1 having a single-surfaced end may be utilized thereby eliminatingwaste of blade stock. The shroud itself in each case is formed withspacing and angling means thereon. The fact that the shroud in each caseis secured to the blade ends by fusion of metal together with thedistortion of the shroud, also permits formation of a shroud strip whichis very light in structure and which still possesses the requisiterigidity and strength. It should furthermore be noted that in each casethe shroud at a blade is formed with a recessed projection incontradistinction to the formation of a shroud with a series ofrojections leaving recesses between them for the blade ends, althoughhere the original projection is in fact altered by the recessing' toform divisional projections. In the form disclosed in Figs. 17 to 20inclusive, the recessed projection at a blade is discontinuous with thecorresponding' recessed projection of an adjacent blade so there will beless tendency to produce eddying of the steam between the blades in thisstructure.

It should be understood that itis not desired to be limited to the exactdetails of construction shown and described except as v required by thesco e of the appended claims, for obvious modi cations will occur to aperson skilled in the art. v

It is claimed and desired to secure by Letters Patent,- l.

1. In combination, a blade having a single-surfaced end, and a shroudhaving a recessed projection for positioning said blade, said shroudbeing secured to said blade at said recess.

2. In combination, a blade having a single-surfaced end, anda shroudhaving a recessed projection for positioning said blade, said shroudbeing secured to Said blade at said recess by fusion of metal.

3. In combination, a plurality of blades each having a single-surfacedend, and a shroud having a projection serially recessed for positioningsaid blades, said shroud being secured to said blades at said recesses.

4. In combination, a plurality of blades each having a single-surfacedend, and a shroud having a projection serially recessed for positioningsaid blades, said shroud being secured to said blades at said recessesby fusion of metal.

5. In combination, a series of blades each having a single-surfaced end,and a shroud secured to the ends of said blades, said shroud havingprojections spanning the spaces between successive blades and saidprojections having surfaces coacting, with side faces of said blades. l

6. In combination, a series of blades each having a single-surfaced end,and a shroud secured to the ends of said blades by fusion of metal, saidshroud having projections spanning the ,spaces between successive b adesand said projections having surfaces coacting with side faces of saidblades.

7. In combination, a series of blades each having a single-surfaced end,and a shroud secured to the ends of said blades by fusion of metal, saidshroud having alined projections spanning the spaces between successiveblades and said projections having surfaces coacting with side faces ofsaid blades.

8. In combination, a blade, and a shroud having a recessed longitudinalv corrugation provided with surfaces for positioning said blade, saidshroud being secured to said blade at said recess. y

9. In combination, a blade, and a shroud having a recessed longitudinalcorrugation provided with surfaces for positioning said blade, saidshroud being secured to said blade at said recess by fusion of metal.

l0. In combination, a plurality of blades, and a shroud having arecessed longitudinal corrugation provided with surfaces for positioningsaid blades, said shroud being secured to said blades at said recesses.

l1. In combination, a plurality of blades, and a shroud having arecessed longitudinal corrugation provided with surfaces for positioningsaid blades, said shroud being secured to said blades at said recessesby fusion of metal.

12. In combination, a plurality of blades, and an imperforate shroudhaving a recessed longitudinal corrugation provided with surfaces forpositioning said blades, said shroud being secured to said blades atsaid recesses.

13. In combination, a plurality of blades, and an imperforate shroudhaving a recessed longitudinal corrugation provided with surfaces forpositioning said blades, said shroud being secured to said blades atsaid recesses by fusion of metal.

In testimony whereof, the signature of the inventor is aiiiXed hereto inthe presence of two Witnesses.

C. EDWIN SEARCH.

Witnesses: G. F. DE WEIN W. H. LIEBER.

